en Adults Hematology & Oncology Adults Hematology & Oncology پژوهشي Original Article <div style="text-align: justify;"><span style="line-height:2;"><span style="font-family:Times New Roman;"><span style="font-size:14px;"><strong>Introduction:</strong> Patients with acute leukemia (AL) are at an increased risk of infection, particularly in acute or critical situations, where timely identification of the cause of infection is crucial. While traditional methods such as microbial cultures remain the gold standard, they require 24&ndash;48 hours for results. In recent years, novel biomarkers like neutrophil CD64 expression have been widely investigated as indicators of infection. However, the diagnostic utility of CD64 within the clinical context of AL patients, especially those who are neutropenic and undergoing treatment, has not been extensively studied. Therefore, this study aimed to assess the diagnostic potential of neutrophil CD64 expression in monitoring the progression of infection and evaluating antibiotic therapy in AL patients complicated by infection.<br> <strong>Methods:</strong> Forty AL patients (20 in the infection group and 20 in the non-infection group), along with 40 healthy controls, were recruited. Data on the percentage of neutrophil CD64+ (%CD64+), CD64 index, C-reactive protein (CRP), white blood cell (WBC) count, and absolute neutrophil count (ANC) were collected.<br> <strong>Results:</strong> Patients with infection exhibited higher %CD64+, CD64 index, and CRP levels compared to those without infection (p<0.001). The sensitivity of both %CD64+ and the CD64 index in diagnosing infection was 90%, while their specificities were 83.3% and 86.7%, respectively. Furthermore, in the infection group, both %CD64+ and the CD64 index were significantly down-regulated after effective antibiotic therapy (p<0.001).<br> <strong>Conclusion: </strong>CD64 shows significant promise in enhancing diagnostic precision and in assessing the effectiveness of antibiotic therapy in AL patients.</span></span></span></div> CD64 index, Infection, Acute leukemia, Antibiotic therapy 23 31 http://ijbc.ir/browse.php?a_code=A-10-1165-1&slc_lang=en&sid=1 Alreza Mohebbi reza.mhb96@gmail.com 100319475328460011283 100319475328460011283 No Department of Hematology and Blood Transfusion, School of Allied Medical Sciences, Tehran University of Medical Sciences, Tehran, Iran. Najmaldin Saki najmaldinsaki@gmail.com 100319475328460011284 100319475328460011284 No Thalassemia and Hemoglobinopathy Research Center, Health Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran. Hossein Karimpourian dr-hossein-k@yahoo.com 100319475328460011285 100319475328460011285 No Thalassemia and Hemoglobinopathy Research Center, Health Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran Shaban Alizadeh alizadehs@sina.tums.ac.ir 100319475328460011286 100319475328460011286 Yes Department of Hematology and Blood Transfusion, School of Allied Medical Sciences, Tehran University of Medical sciences, Tehran, Iran